package com.huishu.gateway.filter;

import com.huishu.gateway.utils.AesEncrypt;
import lombok.extern.slf4j.Slf4j;
import org.reactivestreams.Publisher;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.http.server.reactive.ServerHttpResponseDecorator;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.nio.charset.Charset;

@Component
@Slf4j
public class ResFilter implements GlobalFilter, Ordered {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpResponse originalResponse = exchange.getResponse();
        DataBufferFactory bufferFactory = originalResponse.bufferFactory();
        ServerHttpRequest request = exchange.getRequest();
        String uri = request.getURI().getPath();
        if (uri.contains("export")) {
            // replace response with decorator
            return chain.filter(exchange);
        }
        ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(originalResponse) {
            @Override
            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
                if (!originalResponse.getStatusCode().isError()) {
                    if (body instanceof Flux) {
                        Flux<? extends DataBuffer> fluxBody = (Flux<? extends DataBuffer>) body;

                        return super.writeWith(fluxBody.buffer().map(dataBuffers -> {
                            DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();
                            DataBuffer join = dataBufferFactory.join(dataBuffers);
                            byte[] content = new byte[join.readableByteCount()];
                            join.read(content);
                            // 释放掉内存
                            DataBufferUtils.release(join);
                            // 返回值得字符串
                            String str = new String(content, Charset.forName("UTF-8"));
                            // 把下面加密方法改成你自己的
                            String encryptStr = null;
                            try {
                                encryptStr = AesEncrypt.aesEncrypt(str);
                            } catch (Exception e) {
                                log.error("对返回值加密失败！");
                            }
                            originalResponse.getHeaders().setContentLength(encryptStr.getBytes().length);
                            return bufferFactory.wrap(encryptStr.getBytes());
                        }));
                    }
                }
                // if body is not a flux. never got there.
                return super.writeWith(body);
            }
        };
        // replace response with decorator
        return chain.filter(exchange.mutate().response(decoratedResponse).build());
    }

    @Override
    public int getOrder() {
        return -1;
    }
}

